1. Field of the Invention
In many industrial operations involving the handling of webs, productivity is affected by the difficulty and expense of the handling, itself. Web materials must often be transported without being wrinkled and scratched. Web materials must often be flattened or held or wound at a certain predetermined tension. Web materials must often be treated by heat or by particular fluids. The device of this invention facilitates such web material handling.
2. Description of the Prior Art
U.S. Pat. No. 3,201,935, issued Aug. 24, 1965, discloses a device for determining the tension on a moving web of material. In use of that device, a web is moved over a single arcuate surface with holes at areas of web proximity. Pressure of a gas cushion between the arcuate surface and the web is known to equal the ratio of web tension to arcuate surface radius. The web tension can, therefore, be calculated by determination of the pressure.
United Kingdom Patent No. 2,029,358 published Mar. 19, 1980, discloses a web transport system wherein an air cushion is generated on an arcuate surface for the purpose of providing so-called contactless support of the web.
U.S. Pat. No. 3,807,057 issued Apr. 30, 1974, discloses a web supporting device with a pair of spaced tubular members, a fluid supply means outside the space between the members, and means for removing supporting fluid from between the members.
U.S. Pat. No. 3,678,599 issued July 25, 1972, discloses a web treating device wherein a pair of arcuate spaced-apart web support surfaces are fitted with holes at web proximate areas to withdraw web treatment gases supplied under pressure against a moving web from between the arcuate surfaces.
Pneumatic means for supporting and transporting webs are well known. Single nozzle devices have been made which can be used alone or in tandem or parallel with additional devices as disclosed in U.S. Pat. No. 3,763,571 issued Oct. 9, 1973. Similar single nozzle devices used in multiple series have been disclosed in U.S. Pat. No. 3,498,515 issued Mar. 3, 1970.